Recently, ultrasonic diagnostic apparatuses, X-ray computed tomography apparatuses (CT), and magnetic resonance imaging apparatuses (MRI) have been able to repeatedly acquire data, with high time resolution, on which three-dimensional images are based. Such an apparatus will be described as an X-ray computed tomography apparatus here. This apparatus reconstructs a temporal series of volume data files based on repeatedly acquired projection data by a cone beam reconstruction method or the like. The apparatus generates a series of slice images based on a series of volume data files by MPR (Multi Planar Reconstruction) processing or the like. The series of slice images are reproduced as a moving image.
A region of interest (ROI) may fall outside a slice image due to respiratory motion, pulsation, or the like. During moving image reproduction, the adhesion region between the aorta and a tumor is not depicted in a slice image in some period due to, for example, three-dimensional movement of the tumor and aorta caused by respiratory motion.